Method of heating rolls



Dec. 2, 1930. w. SCHOTTELDREIER METHOD OF HEATING ROLLS Filed Aug. 5, 1927 Fig.1.

Patented Dec. 2, 1930 UNITED STATES,

PATENT OFFICE WILHELM SCHfiTTELDREIER, F NACHRODT IN, WES'IFALEN, GERMANY, :ASSIGNOR T0 -VEREINIG'1E STAELWERKE A. G. DUSSELDORF, A FIRE METHOD or HEATING ROLLS Application filed August 5, 1927, Serial 1T0. 210,884, and in Germany August 7, 1926.

In the production of thin fine sheets of.

metal it is necessary first of all to preheat the rolls to a definite temperature before large and thin sheets can be rolled. It has hitherto 5 been the practice first to roll thick sheets, the rolls 'being' heated and gradually reaching a tem erature that makes it possible for large andt in sheets to be rolled. It takes a fairly lpng time to reach the rolling tem erature m'which is necessary for rolling out t e large and thin sheets. Furthermore, the rollsare frequently broken by reason of the stresses that arise under the application of sudden and localized heating. Moreover, this meth- 0d of heating very readily damages the sur- 7 face of the ground rolls.

It has been proposed to heat the rolls by electric resistance heating. The devices for the purpose are, however, so complicated and expensive, while at the same time the process is so uneconomical thathitherto they have not been put to general practical use.

The invention avoids the disadvantages connected with the known methods referred to.

According to the invention rolls can be preheated to-the necessary temperature in a very short space of time, and with the minimum expenditure of energy. In this connection its important for heatin to proceed from inside outwardly so that t e whole roll shall becompletely heated, the effect being that large and thin sheets can thereu on be rolled. In addition, the cost of the r0 ls is reduced and the capacity of the rolling millfor producing large thin sheets is increased.

- According to the invention the rolls are heated by magnetic hysteresis and eddying currents. -Tl1lS is possible if the poles of close to the rolls so that the rolls are disposed between the poles of the magnets.

The invention is illustrated in the accom- In thedrawings the rolls a are disposed between the poles of two movable alternating same magnet ad acent d1 alternating current magnets are brought current magnets, the cores of the magnets (which are provided with windings e) being divided into separate sheet-metal bundles b in order better to carry oil the heat transmitted from the rolls.

The distance apart of the bundles b is determined by bronze bushes a. The separate of large thin sheets can thereupon c0m-.

mence.

If no alternating current is available, but only direct current, the same procedure as described may be followed, except that the rolls must be rotated if e ual results are to be secured, the period of eating being dependent upon the speed of rotation an the strength of field of the magnets. In this way the process can be adapted to all working conditions.

What I claim and desire to secure by Letters Patentof-the United States is:

1. apparatus for pre-heating the rolls of a sheet rolling mill, comprising U-shaped electro-magnets extending on opposites of said rolls, having the opgglsiget pglpss sgftglg on opposite sides of each roll is a pole of dif- I ferent characterin a dilferent magnet. r 2. An apparatus for pre-heating the rolls of a sheet rolling mill, comprising 'U-shaped electro-magnets extending on opposites of said rolls, having the opposlte poles of the same magnet ad acent different rolls so that on opposite sides of each roll is a pole of different character in a diflerent magnet and means for removing said magnets from the vicinity of the rolls. x- 1 3. An apparatus forpre-heating the rolls. of a sheet rolling mill, comprising U-shaped electro-magnets extending on opposites of said rolls, having the op osite poles of the same magnet adjacent di erent rolls so that on opposite sides of each roll is a pole of different character in a difierent magnet, said magnets having sectional cores comprisin sections'held in spaced relation by meansoi spacers and bolts.

WHHELM 'SGHGTTELDREIER. 

